Idea that i had, as i checked out google (AFTER) finished the project - i saw, i havent been the first one ^_^ - anyways, have been much fun, maybe some time in far future i'll write a making of

Ground is done with displacement, scatter and some particle systems - top is 3 layer (surface, clouds, atmosphere) - surface with displacement. Waterfalls on the edge is a simple bend plane with some deformation, noise, texture and opacity.

Final image was only renderable in layers (on a quad core x64 system 6GB RAM) - but rendered quite quickly, cause no need for gi, raytrace (except for shadows) or such fancyness ^_^